1. Technical Field
The present invention relates to an electronic device, and to a method of manufacturing the same.
2. Related Art
Methods of manufacturing an electronic device so far developed include, for example, the one disclosed in JP-A No. 2003-309215. According to the manufacturing method disclosed therein, a plurality of interconnect layers is sequentially stacked on a supporting substrate to thereby form a multilayer interconnect structure, and then the supporting substrate is removed. On one of the surfaces of the multilayer interconnect structure, exposed by removing the supporting substrate, solder balls are formed so as to serve as an external electrode terminal. On the other surface of the multilayer interconnect structure, an electronic component is flip-chip mounted. Thereby the electronic device, including the multilayer interconnect structure with the electronic component mounted thereon, can be obtained.
Prior art related to the present invention also includes JP-A No. S57-7147, JP-A No. H09-321408, JP-A No. H11-126978 and JP-A No. 2001-53413, in addition to JP-A No. 2003-309215.
The present inventors have recognized as follows. In the foregoing electronic device, to achieve fine connection between the interconnect layer and the electronic component, a resin that is appropriate for micro processing has to be employed for the interconnect layer on the side of the electronic component, among the interconnect layers constituting the multilayer interconnect structure. On the other hand, it is often unnecessary to employ the resin appropriate for micro processing, for the interconnect layer on the side of the solder balls. Accordingly, from the viewpoint of the manufacturing cost of the electronic device, it is desirable to employ a relatively inexpensive resin for the interconnect layer on the solder balls side.
According to the manufacturing method disclosed in JP-A No. 2003-309215, however, the plurality of interconnect layers is sequentially formed on the supporting substrate, for forming the multilayer interconnect structure, as already described. This means that the interconnect layer on the solder balls side is formed prior to the interconnect layer on the electronic component side. Accordingly, a resin lower in thermal decomposition temperature than that used for the interconnect layer on the electronic component side cannot be employed for the interconnect layer the solder balls side. Such restriction imposes a limitation on the selection of the resin to be used for the interconnect layer on the solder balls side, thereby impeding reduction in manufacturing cost of the electronic device.